1. Field of the Invention
The present invention relates to apparatus for reading patterns and more particularly the present invention relates to an automatic pattern reading apparatus especially adaptable for making a tape used for a perforator controlled numerically to provide perforations in such items as a substrate of the type typically used for printed circuit boards for providing holes for mounting components or for through-holes.
2. Description of the Prior Art
At present, few patterns for printed circuits or the like are designed with the intention of locating the perforations used for mounting component parts or for through-holes by numerical techniques. In typical printed circuit patterns, the pattern is formed on a film sheet and manually read by using a perforation reading apparatus.
Since, as mentioned above, the conventional perforation reading apparatus is manually operated, the operator has to visually examine the perforations one by one through a magnifying glass or the like. To align the center of a perforation with the center of a cross mark provided on the magnifying glass, the operator has to move a table on which the pattern is laid or an optical system by hand operation. When alignment is obtained, the operator gives an instruction to a control apparatus such as a computer to read the coordinates and diameter of the perforation.
Such alignment work with the conventional apparatus often makes the operator easily fatigued which leads to errors by the operator in reading perforations or failure to read some perforations.
With the rapid advancement of printed circuit pattern techniques and miniaturization of mounting parts, the packaging density for the print of substrate tends to increase. For these reasons, it is acknowledged in the art that the manual operation system has already reached its limit in view of ability and mental aspects. The manual operation system mentioned above in which the operator aligns the center of a perforation with the center of a cross mark in the magnifying glass, involves another disadvantage. This system lacks the ability to read the diameter of the perforation. Therefore, it was, hitherto, required to previously affix colored marks to the patterns in a form of film sheet using different colors for different perforation diameters. This necessitates a work prior to the perforation reading and additional time for the previous work.